In a hard disk drive (HDD), a slider, supported by a suspension arm, “flies” over a surface of a rotating magnetic disk at a high velocity, reading data from and writing data to concentric data tracks on the disk. Currently the areal density of recording magnetic disk drive is rapidly increasing at a CAGR of 40%. The slider fly height continues to be reduced, enabling increased signal strength between the sensor and the media. The curvature profile of the slider air bearing surface (ABS) is a critical parameter for fly height control. For example, it has been found that two important characteristics of the slider to achieve and maintain the desired flying characteristics for the slider are crown and camber.
FIG. 1A depicts a slider 100 having camber 102 and crown 104 on an ABS side 110 of the slider 100. The slider 100 also has a backside 120 opposite to the ABS side 110 and two substantially parallel sidewalls 130 perpendicular to the ABS side and backside. Crown 104 is along an air flow direction 105, while camber 102 is along a direction perpendicular to the air flow direction 105. As illustrated in FIG. 1B, camber 102 is measured by a deviation or a delta change 109 from a planar surface in a direction perpendicular to the air flow direction 105 with a convex shape (having a positive delta change as shown) defined as positive camber and a concave shape (having a negative delta change) defined as negative camber. Crown 104 is measured by a deviation or delta change (not shown) from a planar surface in the air flow direction 105 with a convex shape (having a positive delta change) defined as positive crown and a concave shape (having a negative delta change) defined as negative crown.
Neither negative camber nor negative crown of the ABS is desirable because this not only leads to variation in the flying height but also makes it more likely that the edges of the slider will damage the spinning media should there be inadvertent contact with the media, caused, e.g., by an operational shock. In this regard, the camber is especially known to impact the reliability of an operating HDD. The ABS surface is as little as 8 nm from the rotating disk. The camber profile impacts the clearance budget as the highest camber point will be the point of closet proximity to the spinning media. During HDD start up and shut down the slider is subjected to load/unload (L/UL) while the media is rotating. Control of the camber is important during L/UL as it can behave much like a knife edge digging into the media creating disk ding and/or disk scratches resulting in lost data or complete drive failure. For these reasons, it is desirable to have a positive crown in a range of between about 0 and 0.4 μ-inch and a positive camber in a range of between about 0 and 0.6 μ-inch.
Conventionally, camber adjustment during the slider fabrication process has utilized several technologies such as: spherically curved lapping plates, back side grinding, diamond-tip scribing, laser scribing, backside lapping, backside reactive ion etching, ion beam etching, and other methods. The aforementioned prior art camber adjustment techniques are performed prior to a slider parting process and manipulate the stresses on the slider backside 120 or on the slider ABS side 110.
FIG. 2 is a diagram illustrating a prior art slider parting process for separating a slider from a slider bar. In the illustrated prior art slider parting process, a rotating blade 205 is made to move towards a slider bar 201 comprising a plurality of sliders 200 in a cutting direction 209. The slider bar 201 is affixed to a fixture (not shown) in such a way that an ABS side 210 of the slider bar 201 is parallel to the cutting direction 209. In another slider parting process, the slider bar 201 is affixed to the fixture in such a way that its ABS side is facing towards the cutting direction. In both cases, assuming that the surfaces of the original slider bar are initially flat, a parted slider can have negative camber, requiring a separate camber adjustment process (e.g., a relief cut process) performed after the slider parting process to generate positive camber.
It is therefore desirable to have an apparatus and method for controlling camber (e.g., generating a pre-determined positive camber) of a slider during a slider parting process without requiring a separate camber adjustment process before or after the slider parting operation.